Tempering a spear?

[Mark Wargo New2bs]

Howdy all. Well, I have successfully forged, ground, normalized, and quenched my first spear point out of 5160 steel. I put it in the oven for two hours at 400 F to relieve stress. Tomorrow I will do another temper cycle. The intended use of the spear is to kill a hog. I know that in that case toughness wins out over edge holding, as it really only needs to hold an edge for a couple kills and can be resharpened between hunts. What temperature would folks suggest for the final tempering cycle to maximize toughness/springiness yet maintain a decent edge?

Mark

[bigfootnampa]

I'd say you are likely done. Try it out, test file it and if you can get a decent bite with a file you are good to go. A couple of hours at 400 degrees is about what I would do... and you've got that already. Why do you think you need more? With 5160, basically a spring steel, you should have a pretty tough blade there. You could go to 450 degrees for another hour or two... but I doubt it's needed.

[Mark Wargo New2bs]

Just lack of experience. I know what I've read about tempering knives and heat treating in general, but I also know there is often a great deal of difference in knowing something and doing something. I know what the "book" says the RC hardness should be for 5160 tempered at that degree, but I don't have any knowledge of how that relates to flexibility. I don't want to test it to destruction to find out heheh. I also want to insure I don't have any retained austenite to weaken the blade.

Mark

[Mark Wargo New2bs]

Thanks for the input and insight guys. I did go ahead and do another temper cycle at about 450. I think the oven runs a little hot based on the temper colors I've seen on previous heat treats, so i'm thinking it's a bit closer to 500. I plan to get it reasonably sharp and try it on a variety of targets to test for toughness prior to the big hunt. If it is going to fail, I'd prefer it do so on something other than an angry pig. I'll post pics once it's mounted on the haft. I had thouht I'd polish it back to silver, but I think I'll leave it as quenched.

Mark

[Mark Wargo New2bs]

The blade is a dark off-black color from the oil quench. After the 450 in the oven the edges that were silver are blue-ish.

Mark

[Steve Sells]

The blade is a dark off-black color from the oil quench. After the 450 in the oven the edges that were silver are blue-ish.

Mark

I go for the bluish-to-brown on heavy beater things like machete, spear, axe, heavy contact swords. at least 2x for addressing the retained austinite.